Method of controlling pests using certain ketones of thiophene

ABSTRACT

Certain ketones of substituted furans and thiophenes of the formula   WHERE Y is for example 3-(2,5-dichlorothienyl), o-bromophenyl, etc., the R&#39;&#39;s are for example hydrogen, halogen, etc., and X is oxygen or sulfur, are useful for controling pests, particularly acarids (mites and ticks), insects and nematodes.

United States Patent [191 Ariyan et al.

[ Sept. 9, 1975 METHOD OF CONTROLLING PESTS USING CERTAIN KETONES OF THIOPI-ENE [75] Inventors: Zaven Stephen Ariyan, Woodbury;

Robert Edward Grahame, Jr., Waterbury; Winchester Loomis Hubbard, Woodbridge, all of Conn.

[73] Assignee: Uniroyal, Inc., New York, NY.

[22] Filed: Nov. 13, 1972 [21] Appl. No.: 306,044

FOREIGN PATENTS OR APPLICATIONS 1,228,744 4/1971 United Kingdom 424/275 Primary ExaminerAlbert T. Meyers Assistant Examiner-Dale R. Ore Attorney, Agent, or Firm-James J. Long [5 7] ABSTRACT Certain ketones of substituted furans and thiophenes of the formula where Y is for example 3-(2,5-dichlorothienyl), obromophenyl, etc., the R's are for example hydrogen, halogen, etc., and X is oxygen or sulfur, are useful for controling pests, particularly acarids (mites and ticks), insects and nematodes.

6 Claims, No Drawings METHOD OF @UNTROLLKNG PESTS USING CERTAllN KETQNES OF THKOPHENE This invention relates to a method of controlling pests, including acarids, using certain ketones of substituted furans and thiophenes.

British Pat. No. 1,228,744, Boots Pure Drug Co., issued Apr. 15, 1971, discloses control of nematodes with certain ketones of substituted furans or thiophenes, wherein the ketone group is in the 2-position of the furan or thiophene ring. In contrast, in the presently employed chemicals the ketone group is in the 3-position of the furan or thiophene ring; such chemicals have, surprisingly, been found to be effective acaricides.

US. Pat. No. 2,690,413, .lanes, et al., Sept. 24, 1954, discloses control of insects and nematodes by fumigation, using certain acetylated halogenated thiophenes and thiolanes. The chemicals used in the present invention are not acetylated bodies, and unexpectedly have acaricidal properties.

Y. L. Goldfarb and M. S. Kondakova, lzvest. Adad. Nauk. S.S.S.R., Otdel. Khim. Nauk. 1956, 495-504; CA: 1956: 167450, disclose bis-3-(2,5-dimethylthienyl)-ketone.

Ng, Ph. Buu Hoi and Denise Lavit, J. Chem. Soc. 1958, l72l3 (C. A. 52, 16330 i) disclose 2,5- dichloroQ-(Z-thenoyl) thiophene.

The chemicals employed as pesticides in the pest control method of the invention are ketones of furans and thiophenes having the formula where Y represents a substituted or unsubstituted heterocyclic radical, a substituted or unsubstituted aromatic radical, or an alkenyl radical, R, R and R" are the same or different and may be hydrogen, alkyl or halogen, and X is oxygen or sulfur.

in the chemicals employed in the invention, preferred values for Y are C -C alkenyl (e.g., vinyl, propenyl, butenyl, pentenyl, octenyl) or furyl, thienyl and phenyl without substitution or furyl, thienyl and phenyl substituted with one, two, or more substituents (such as halogen [e.g chlorine, bromine], lower alkyl [e.g., methyl, ethyl], and the like), R is preferably hydrogen, halogen (e.g., chlorine, bromine), or C -C alkyl (e.g., methyl, ethyl, butyl, octyl) and R and R" are preferably halogen (e.g., chlorine, bromine) or C -C alkyl (e.g., methyl, ethyl, butyl, octyl), X being of course oxygen or sulfur as previously indicated. Most preferred are chemicals in which Y is a heterocyclic or aromatic moiety.

The pesticidal chemicals useful in the invention are typicaily prepared by reacting, according to a Friedel- Crafts synthesis, a 2,5-disubstituted or 2,4,5-trisubstituted furan or thiophene with an appropriate acid chloride The acid chlorides employed may be alkenyl', aromatic or substituted aromatic, heterocyclic or substituted heterocyclic. Among the starting acid chlorides are those of the formula Y-C-Cl where Y is an alkenyl group having 2 to 8 carbon atoms. Acid chlorides leading to new chemicals of the invention also include those of the formulas:

where R and R,, are the same or different and are hydrogen or substituents such as halogen, alkyl, etc.; also where X, is oxygen or sulfur, and

.C-Cl

where R and R; are the same or different and are hydrogen or various substituents such as halogen, alkyl, etc., and X,, is oxygen or sulfur.

Preferred chemicals include those in which Y is 2- thienyl or 3-( 2,5-dihalothienyl), X is sulfur, R-is hydrogen, and R and R are halogen.

Almost all of the present ketones are thick viscous oils somewhat yellow in color and they may be distilled readily at reduced pressures. They are soluble in most organic solvents. These thick oils may gradually solidify on standing over a period of time. They are usually prepared in 5090% yield by the method described.

The principal pests against which the present biocidal process is employed are acarids such as mites and ticks,

although the chemicals are also remarkable for their effectiveness in the control of other pests, notably insects and nematodes. Mites and insects are important in agriculture and as pests of man and animals. Nematodes are also important pests, both in agriculture and as internal parasites of man and animals. The chemicals of the present invention have the ability to destroy parasitic nematodes and their eggs and larvae.

Pest control may be accomplished by various methods including soil application for control of plant parasitic nematodes, foliar application for mite and insect control, and dissolving of the chemicals in water for the control of aquatic pests such as mosquito larvae.

The invention is applicable to control of such mites as apple rust mite Aculus sc/zlechtendali (Nalepa) Banks grass mite Oligonychus pratensis (Banks), brown mite Bryobia arborea Morgan and Anderson, citrus red mite Panonychus citri (McGregor), citrus rust mite Phyllocoptruta oleivora (Ashmead), clover mite Bryobia praetiosa Koch, cyclamen mite Steneotarsonemus pallidus (Banks), European red mite Panonychus ulmi (Koch), McDaniel spider mite Tetranychus mcdanieli MdGregor, Pacific spider mite Tetranychus paczficus McGregor, peach silver mite Aculus cornmus (Banks), six-spotted mite Eotetranychus sexmaculatus (Riley), straberry spider mite Tetranychus atlanticus McGregor, Texas citrus mite EutetranyC/lus banksi (McGregor), two-spotted spider mite Tetranychus urticae (Koch), and Willamette mite Eotetranychus willamettei Mc- Gregor, as well as such plant parasitic nematodes as root knot Meloidogyne incognita, sting Belonolaimus longicaudatus, surgarbeet Heterodera schaclztii, lance Hoplolaimus sp., stubby root Trichodorus christiei, and awl Dolichodorus heterocephalus; also such saprophytic nematodes as Panagrellus redivivus and such insects as the yellow fever mosquito Aedes aegypti.

In general, the present pesticidal agents may be applied in various manners. They may be applied to loci to be protected against pests as dusts when admixed with or absorbed in powdered solid carriers, such as various mineral silicates, e.g., mica, talc, pyrophillite and clays, or as liquids or sprays when in a liquid carrier, as in solution in a suitable solvent, such as acetone, toluene or kerosene, or dispersed in a suitable non-solvent medium, for example, water. In protecting plants (the term including plant parts), which are subject to attack by mites or other pests, the chemicals are preferably applied as aqueous emulsions containing a sur faceactive dispersing agent, which may be an anionic, nonionic or cationic surface-active agent. Such surface-active agents are well known and reference is made to U.S. Pat. No. 2,547,724, columns 3 and 4 for detailed examples of the same. The chemicals may be mixed with such surface-active dispersing agents, with or without an organic solvent, as insecticidal concentrates for subsequent addition of water to make aqueous suspensions of the chemicals of the desired concentration. The chemicals may be admixed with powdered solid carriers, such as mineral silicates, together with a surface-active dispersing agent so that a wettable powder may be obtained, which may be applied directly to loci to be protected against pests, or which may be shaken up with water to form a suspension of the chemical (and powdered solid carrier) in water for application in that form. The chemicals may be applied to loci to be protected against pests by the aerosol method. Solutions for the aerosol treatment may be prepared by dissolving the chemical directly in the aerosol carrier which is liquid under pressure but which is a gas at ordinary temperature (e.g., C.) and atmospheric pressure, or the aerosol solution may be prepared by first dissolving the chemical in a less volatile solvent and then admixing such solution with the highly volatile liquid aerosol carrier. The chemicals may be used admixed with carriers that are active of themselves, for example, other insecticides, fungicides, or bactericides.

The following preparations illustrate the synthesis of chemicals employed in the invention.

CHEMICAL 1 Preparation of 2-Thenoyl-3-(2,5-dibromothiophene).

To 48.2 gr. (0.2 mole) of 2,5-dibromothiophene and 29.2 gr. (0.2 mole) of 2-thenoyl chloride in 400 c.c. of dry carbon disulfide, anhydrous aluminum chloride (26.6 gr., 0.2 mole) is gradually added with efficient stirring at room temperature. A purple coloration gradually develops and HCl is evolved. This mixture is well stirred overnight and heated on a steam bath for two more hours prior to work up. The organic layer is then separated and washed several times with a sodium bicarbonate solution and dried over sodium sulfate. The solvent is then removed and the crude product subjected to vacuum distillation. Bpt. 265 at 1.0mm. Calc. for C H OS Br :C-=3O.75; H= 1.05; S= 18.47; B1: 45.34; Analyzed: C 30.71; H 1.15; S= 18.23; Br 45.41.

CHEMICAL 2 Preparation 3-( 2,5-dimethylthienyl -3-( 2,5-dibromothienyl)- ketone To a well stirred mixture of 2,5-dimethyl-3-thenoyl chloride (0.07 mole) and 2,5-dibromothiophene (0.065 mole) in 300 cc anhydrous carbon disulfide, aluminum chloride (0.07 mole) is gradually added. A complex soon forms and HCl evolves. The mixture is well stirred at room temperature for 15 hours and subsequently heated on a steam bath for 3 hours. The complex is broken down with ice/HCl and solvent extracted and this is followed by a similar work up as the above experiment in drying and removing the solvent. The yellow oil is distilled over at /0.5 m.m. Calculated for C H OS Br S 16.9; Analyzed S 16.4.

CHEMICAL 3 Preparation of Bis-3-(2,5 -dichlorothienyl)-ketone To a well stirred mixture of 2,5-dichloro-3-thenoyl chloride (0.028 mole) and 2,5-dichlorothiophene (0.025 mole) in dry carbon disulfide (200 c.c.), aluminum chloride (0.025 mole) is gradually added. A deep coloration ensues and the mixture is stirred for 15 hours and subsequently heated on a steam bath for 3 hours. Usual work up and distillation yield a yellow oil, Bpt. ISO/1.0 mm. C H OS CI Calc., C 32.60; H 0.62; S 18.9; C1 42.6; Found: C 33.14; H 0.87; S 19.3; C1= 41.7.

CHEMICAL 4 Preparation of Bis-3-(2,5-dimethylthienyl)ketone.

To a well stirred mixture of 2,5-dimethyl3-thenoyl chloride (10.0 gr., 0.057 mole) and 2,5-dimethylthiophene (6.3 gr., 0.055 mole) in carbon disulfide (300 c.c.), aluminum chloride (7.6 gr., 0.057 mole) is gradually added. HCl evolves and usual procedure gives an oil b.p. 137/0.5 which on standing crystallizes to colorless crystals. mpt. 61 (Y. L. Goldfarb and M. S. Kondakova, Izvest. Adad. Nauk. S.S.S.R., Otdel. Khim. Nauk. 1956, 495-504; CA: 1956: 167450).

CHEMICAL 5 CHEMICAL 6 Preparation of 2-Thenoyl-3-(2,5-dimethylfuran) To a well stirred mixture of 2,5-dimethylfuran (9.6

6 gr., 0.1 mole) and Z-thenoyl chloride (14.6 gr. 0.1

mole) in 250 cc carbon disulfide, aluminum chloride 13.3 gr., 0.1 mole) is gradually added. The usual reaction time, work up and distillation give a yellow oil Bpt.

5 117 120/0.5 mm. Calc. for c n o s; C: 64.03; H

4.88; S 15.54; Found: C 64.51; H 5.00; S 15.36.

CHEMICALS 7 29 Using the same procedure as in the foregoing preparations, additional chemicals are made as summarized in Table I, which includes data on the boiling point and structure of chemicals 1 6 as well as 7 29.

Table 11 presents analytical data on the chemicals; Table 111 lists bromine analysis data on certain chemicals.

Table I Structure and Boiling Point of Chemicals 1 29 Chem. Y B.pt/mm X R R R" 7 CH;,CH=CH /04 0 H CH CH 8 CH;,CH=CH /10 S H CH CH 9 o-Bromophenyl 170/05 5 H Br Br 10 p-Bromophenyl 170/05 S H Br Br 1 l Phenyl /05 S H CH CH 12 p-Chlorophenyl 137/05 S H CH CH, 13 p-Chlorophenyl 160/05 S H Br Br 14 2,4-Dichlorophenyl /03 0 H CH CH;, 15 3 .4-Dichlorophenyl 145/04 0 H CH; CH 16 2 4-Dichlorophenyl 143/03 S H CH C11 17 3 4Dichlorophenyl 155/05 S H CH CH 18 3.4-Dichloropheny1 190/05 S H Br Br 19 2-Furyl /04 S H Cl Cl 20 Z-Furyl /08 0 H CH CH 21 Z-Thienyl /03 S H Cl Cl 22 Z-Thienyl 137/008 S H CH CH 1 2-Thienyl 16l/1.0 S H Br Br 23 2Thienyl 81/05 S Br Br Br 24 3-(2,5-Dibromothienyl) 162/03 S H Br Br 3 3-(2.5-Dichlorothienyl) 150/1 S H C1 C1 4 3-( 2,5-Dimethylthienyl) 160/05 S H CH CH 5 3-( 2,5-Dich1orothienyl) 160/07 S H Br Br 2 3-(2,5-Dimethylthienyl) 160/05 S H Br Br 25 3-( 2.5Dimethylthienyl) /05 S H C1 C1 6 Z-Thienyl 1 17/05 0 H CH CH 26 Phenyl 132/05 S C- H CH CH; 27 2-Thieny1 155/03 S C H C1 C1 28 Z-Thienyl S 2": 3 29 2-( S-Bromothienyl) 150/05 S H C1 C1 Table 11 Analytical Data (Cale) (Found) Chem. General Formula C Cl C H S C1 22 C H OS 59.41 4.53 28.85 59.46 4.50 28.54 19 C H O SC1 44.10 1.62 28.70 43.58 1.92 28.74 20 C H O 69.48 5.30 69.84 5.80 14 C H 0O CI 57.00 3.78 26.00 56.96 3.79 26.30 15 C H O C1 26.00 26.61 12 C H OSCI 62.25 4.42 12.80 61.56 4.44 12.87 13 C 1-1 OSC1Br 36.00 1.58 10.04 37.06 1.78 9.87

9 C H OSBn, 32.20 1.19 33.10 1.27 10 C H OSB 32.20 1.19 32.10 1.24

3 C H OS Cl 32.60 0.62 18.9 42.6 33v 14 0.87 19.3 41.7 5 C,,H OS C1 Br- 16.8 17.4 2 C,,H,.OS Br 16.9 16.4

25 C H,.OS Cl 46.5 2.78 22.00 46.6 2.99 22.01 21 C H OS Cl 41.0 1.54 24.4 27.0 41.2 1.61 24.1 27.1 16 C H OSCh, 54.80 3.56 24.80 54.82 3.48 24.47 17 C H OSCb 54.80 3.50 24.80 54.67 3.53 24.18

1 C H OS Br 30.71 1.15 18.23 30.75 1.05 18.47 6 C H O S 64.03 4.88 15.54 64.51 5.00 15.36

Table ill Table EV -Continued Bromine Analysis The following examples will serve to illustrate the practice of the invention in more detail.

EXAMPLE l This example illustrates the present process for controlling mites.

Cotton, in the primary leaf stage and grown in twelve ounce cups under greenhouse conditions at 7075F, is used in this test. Two plants, for a total of four leaves, are tested at each chemical concentration. The upper leaf surfaces of the untreated leaves are ringed with a one inch diameter circle of tanglefoot, a non-toxic adhesive preparation used on fly papers and for ringing trees. This serves to confine the mites to the upper leaf surface. Mites are transferred to the prepared leaves by placing sections of broad bean leaves heavily infested with two-spotted spider mites, Tetranychus urticae I..., within the border of the adhesive preparation.

0.2 gram of chemical to be tested may be mixed with one drop of a commercial surface-active dispersing agent such as polyoxyethylated vegetable oil [(eg. castor oil) as represented for example by such commercial preparations as Emulphor El" (trademark)], dissolved in 2-4 ml of acetone and brought to a total volume of 100 ml with distilled water. Dilutions of 400 ppm and 80 ppm are made from this solution using distilled water containing one drop of polyoxyethylated vegetable oil per 100 ml distilled water.

The plants are sprayed with dispersions of the chemicals at the various concentrations and the check plants Control of Mites Control at Chem. 2000 400 N0. Chemical PPM PPM 25 2,5-Dimethyl-2.5'-dichloro-3,3'- lOO 100 dithienyl ketone EXAMPLE ll This example illustrates the effectiveness of the chemicals as contact poisons for controlling nematodes.

Eighty mg of chemical is mixed with one drop of a commercial surface-active dispersing agent (isoctylphenyl polyethoxy ethanol), dissolved in 2-4 ml acetone, and brought to a total volume of ml with distilled water. This chemical suspension is added to, and manually mixed with, 1.5 pounds of sandy soil severely infested with rootknot nematodes of the genus Meloidigyne. This amount of chemical is equivalent to a rate of 240 pounds per acre. All dosages are based on the weight of an acre of soil 6 inches deep as being two million pounds. Dosages of 120 pounds per acre and sixty pounds per acre are also included. The treated 1.5 pounds of infested soil is filled into two twelve-ounce styrofoam cups and placed in the greenhouse at a temperature of approximately 75F. Untreated noninfested and infested checks are included in the test.

One week later five cucumber seeds are planted in each treated and untreated cup. The test is kept in the green house and watered regularly. Two weeks after planting the seeds the cucumber roots are inspected for galls caused by the root-knot nematodes. The results are recorded in percent control. Results with the chemicals employed in the present invention are shown in Table V.

TABLE V Control of Nematodes Percent Control At are sprayed with aqueous solutions containing the sur- 40 (33cm Ch l L sg O. emlc' face-act1ve agent and acetone without the chemicals. 3 5/ S/ 5 The sprayings thoroughly wet the upper surface of 1 the leaves. The plants are returned to the greenhouse, hiophene 100 f h d Th 2l 2-Thenoyl-3-( 2.5-dichloro allowed to dry, and a count 0 t e mites lS ma e. e thiophene) 100 80 60 plants are held in the greenhouse for five days. A final 13 2,5-Dibromo-3-(p-chlorobenzoyl) thiophene 100 40 0 count of the living mites remalnmg on the leaves is then 8 zvsbimethymycrmonoyl made. The percent control IS found by using the followthiophene 90 0 0 1 23 2-Thenoyl-3-(2,4,5-Tri mg formu a bromothiophene) l()() 80 40 live mites on) 70 live mites on 24 2 2 5 5' b 3 3' check plants treated plants dithienyl ketone 80 0 0 Percent Control 100 live mites on check lants P EXAMPLE n1 Typical results are Shown in Table IV This example illustrates the effectiveness of the invention for controlling insects. in this test, fourth instar Table IV larvae of Aea'es aegyptz (L.) mosquitoes are used. After Control of Mit s Control at hatching, the larvae normally reach this stage of devel- Chem. 2000 400 t d, t 0

No. Chemical PPM PPM opmen We y d 3 2 b b 1 100 88 One ml ofacetone and 100 ml of water IS added to 10 9 fi ggigig romo ml of each chemical to be tested. This gives a concen- 10 y 100 83 6O tration of 100 ppm. A dilution of 10 ppm is made from thiophene 13 2.5-Dibromo3-(p-chlorobenzoyl) 100 91 thls Solutlonthiophene Twenty-five ml portions of each concentration of 17 chemical to be tested, replicated once, are placed in thwpene) 63 r t t b d r 5 t 25 't 1- dd d l 2-Thconoyl-3-(2,5-dibromothiophene) I00 100 es u es mm 0 mosqu' O l are a e 24 2,2,5,S'-Tetrabrom0-3 3'-dithienyl 100 100 65 Checks without the chemical and plain water checks ketone r are als 3 2,2,5,5-Tetrachloro-3.3'-dithienyl 100 100 o O Included The tubes drg h darknesgat kewne F for 72 hours. At the end of this period, both live 5 .5-Dichlor0-2'.5dibromO3. I00 and dead larvae are counted and the percent mortality dithienyl ketone ,1 l, t d Th I f h l I d 2 zsnimethylvzxs, dibromo 33, 100 '00 ca cu a e c percent morta ity o t e arvae treate dithienyl ketone with the present chemicals is shown in Table VI.

Control of Insects Percent of Mortality at Chem. 100 l I No. Chemical PPM PPM PPM 7 2,5-Dimethyl-3- crotonoyl furan I00 8 2,5-Dimethyl-3- crotonoyl thiophene 100 100 0 9 2,5 Dibromo3( 2-bromobenzoyl) thiophene I00 I00 0 I0 2,5-Dibromo-3-(4-bromobenzoyl) thiophene 100 I00 I00 I l 2,5-Dimethyl-3-benzoyl thiophene I00 95 12 2,5-DimethyI-3-(p-chlorobenzoyl) thiophene I00 I00 0 l 3 2,5Dibromo 3-( pmhlorobenzoyl) thiophene I00 85 l4 2,5-DimethyI-3-(2,4-dichlorobenzoyl) furan l 00 O I5 2,5-Dimethyl-3-( 3 ,4-dichlorobenzoyl) furan 100 80 l 6 2,5-Dimethyl-3( 2,4dichlorobenzoyl) furan I00 I O0 I7 2,5Dimethyl3-( 3,4-clichlorobenzoyl) thiophene I00 90 20 18 2,5-Dibromo-3-( 3,4-dichlorobenzoyl) thiophene 100 100 100 I9 2Fur0yl-3(2,5-dichl0r0thiophene) I00 100 36 20 2-Furoyl-3-(2,5-dimethylfuran) I00 21 2Thenoyl-3-(2,5-dichlorothiophene) I00 I00 0 22 2-Thenoyl-3-( 2,5-dimethylthiophene) 100 100 0 l 2-Thenoyl3( 2,5dibromothi0phene) I00 I00 50 23 2-Thenoyl-3 2,4,5-tribromothiophene) I00 I00 0 24 2,2,5 5'-Tetrabromo3 3'-dithienyl ketone I00 1 00 20 3 2,2',5,5'Tctrachloro-3,3'dithienyl ketone I00 I00 100 4 2,2 ,5,5 -Tetramethyl-3,3 -dithienyl ketone 100 l 00 6 5 2,5-Dichloro 2fl5-dibromo-3,3'-

dithienyl ketone I00 100 I00 2 2,5-Dimethyl-2',5' dibromo-3,3

ketone I O0 100 O 25 2,5-Dimethyl-2,5"dichl0ro-3,3-

dithienyl ketone I00 I00 0 6 2-Thenoyl-3-(2,5-dimethylfuran) I00 I00 EXAMPLE IV Table VII gives a selective comparison between (i) certain chemicals employed in the invention (ii) certain chemicals pertinent to US. Pat. No. 2,690,413, lanes et al., and (iii) certain chemicals pertinent to British Pat. No. 1,228,744 Boots Pure Drug Co., as follows:

Chemical (i) Chemicals of the present process Table VII Shows the results of evaluating the chemicals as acaricides using the procedure previously described.

TABLE VII Activity Comparison on Mites Percent Control at The superiority of the chemicals used in the invention, Chemicals Nos. 1, 24 and 3, is manifest in Table VII.

We claim:

1. A method of controlling acarids comprising applying to a locus, subject to attack by acarids, an effective acaricidal amount of a ketone of a substituted thiophene having the formula wherein Y is selected from the group consisting of 2- thienyl and 3-(2,5-dichloroor dibromothienyl),

R is hydrogen and R and R" are chlorine or bromine.

2. A method as in claim 1 in which the ketone is 2- thenoyl-3-( 2 ,5 -dibromothiophene 3. A method as in claim 1 in which the ketone is bis- 3-(2,5-dibromothienyl)-ketone.

4. A method as in claim 11 in which the ketone is bis- 3(2,5-dichlorothienyl)-ketone.

5. A method as in claim 1 in which the ketone is 2- thenoyl-3-( 2 ,5 -dichlorothiophene 6. A method as in claim 1 in which the ketone is 3- (2,5-dichlorothienyl)-3'-(2,5-dibrom0thienyl)-ketone. 

1. A METHOD OF CONTROLLING ACARIDS COMPRISING APPLYING TO A LOCUS, SUBJECT TO ATTACK BY ACARIDS, AN EFFECTIVE ACARICIDAAL AMOUNT OF A KETONE OF A SUBSTITUTED THIOPHENE HAVING THE FORMULA
 2. A method as in claim 1 in which the ketone is 2-thenoyl-3-(2, 5-dibromothiophene).
 3. A method as in claim 1 in which the ketone is bis-3-(2,5-dibromothienyl)-ketone.
 4. A method as in claim 1 in which the ketone is bis-3-(2,5-dichlorothienyl)-ketone.
 5. A method as in claim 1 in which the ketone is 2-thenoyl-3-(2, 5-dichlorothiophene).
 6. A method as in claim 1 in which the ketone is 3-(2,5-dichlorothienyl)-3''-(2,5-dibromothienyl)-ketone. 